Critical time window for rehabilitation after a stroke

The study suggests there is a critical window after a stroke in which intensive rehab yields the best results. imtmphoto / Shutterstock

Every 40 seconds, an American has a stroke. About 750,000 new strokes occur in the United States each year.

Restoring brain function after a stroke remains a challenge. Functional recovery from brain damage requires networks of nerves to adapt and reorganize. This “neuroplasticity” naturally occurs during early development. But studies in rodents suggest that there is a brief period of similarly high neuroplasticity after a stroke. Intensive motor training provided to rodents during this window can lead to nearly full recovery. But no evidence for a similar recovery window in humans has previously been found.

To find out if such a window exists in people, a team led by Dr. Alexander Dromerick of Georgetown University Medical Center and MedStar National Rehabilitation Hospital conducted a randomized phase II clinical trial. NIH’s National Institute of Neurological Disorders and Stroke (NINDS), Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and National Institute on Deafness and Other Communication Disorders (NIDCD) supported the study. Results appeared in the Proceedings of the National Academy of Sciences on September 20, 2021.

The researchers recruited 72 patients from a rehabilitation hospital in Washington, DC. They randomly assigned participants to one of four groups. All participants received standard stroke rehabilitation therapy. Those in three of the four groups received an extra 20 hours of intensive motor skills therapy. In the first group, the extra therapy began within 30 days of stroke onset. In the second group, extra therapy began 2-3 months after stroke onset. In the third, it began 6-7 months after stroke onset. Participants in the fourth (control) group received no extra therapy.

The researchers assessed arm and hand function at various points before and after treatment, up to 12 months after stroke onset. People in the 2–3 month therapy group showed the greatest improvement one year after their strokes. Participants in the 30-day group showed smaller but still significant improvement. By contrast, participants in the 6-7 month group showed no significant improvement over controls.

“Our results suggest that more intensive motor rehabilitation should be provided to stroke patients at 60 to 90 days after stroke onset,” co-author Dr. Elissa Newport says.

“Previous clinical trials have found few or very small improvements in motor function post-stroke, so our research could be an important breakthrough in finding ways we can make substantial improvements in arm and hand recovery,” Dromerick says.

The results strongly suggest that there is a critical time window for rehabilitation following a stroke. For this study, that window was 2-3 months after stroke onset. Larger clinical trials are needed to better pin down the timing and duration of this critical window. A larger trial could also determine what dose of therapy would achieve the best results during this window.

—by Brian Doctrow, Ph.D.